How does atherosclerosis affect the microstructure of human femoral arteries: a 3D microstructural characterization study

Details

Supervisors

Kerckhofs, Greet

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil biomédical, à finalité spécialisée

Abstract

Atherosclerosis, characterized by the accumulation of fatty deposits and heightened inflammatory response in the tunica intima, is a prevalent disease affecting arteries. Despite a reduced atherosclerosis-related mortality rate in past years, it remains a leading cause of death globally due to complications like heart disease and strokes. From initiation to advanced stages, atherosclerosis induces significant changes in arterial walls, including smooth muscle cells migration and necrotic core formation. Although there is a considerable amount of research concerning atherosclerosis, certain phenomena, such as the formation of calcifications, are still under investigation. A few hypotheses are proposed by the literature, including smooth muscle cells depositing calcium then becoming microcalcifications that will merge into larger calcifications, or macrophage death that causes calcifications. Theses hypothesis, and other characteristics of atherosclerosis such as the number of calcifications are investigated throughout this master thesis. Initial 3D low-resolution imaging (30 and 10 µm) thanks to X-ray microcomputed tomography enables quantitative analysis of calcifications. At first, the total volume of calcifications and the form of calcifications are compared among patients. Two forms are spotted: circular regular form and irregular chunks. The volume analysis indicates that the amount of calcification can differ a lot between two patients. Then, each calcification is classified depending on its volume, and depending on its density. This analysis tends to confirm that small calcifications merge into large ones. These analyses also suggest that the formation and development of calcifications are an progressive process. Additional low-resolution imaging is performed on a sample containing a stent, producing images full of artifacts. Despite these artifacts, calcifications are visible and they penetrate the stent, indicating that the stent does not effectively stop disease progression. These findings necessitate improved imaging methods to reduce artifacts and better visualize arterial microstructure. High-resolution X-ray microcomputed tomography images of stained arteries offers further qualitative insights, identifying microcalcifications within atheromas and supporting the hypothesis that various calcification types can form. The detection of numerous small grains within larger calcifications supports the hypothesis that the formation process involving smaller calcifications merging into larger structures.